A number of picolinic acids and their pesticidal properties have been described in the art. U.S. Pat. No. 6,784,137 B2 and U.S. Pat. No. 7,314,849 B2 disclose a genus of 4-amino-6-arylpicolinic acids and their derivatives and their use as selective herbicides, particularly for rice and cereals such as wheat and barley. WO 2005/063721 A1, WO 2007/082076 A1, U.S. Pat. No. 7,863,220 B2, U.S. Pat. No. 7,300,907 B2, U.S. Pat. No. 7,642,220 B2, and U.S. Pat. No. 7,786,044 B2 disclose certain 6-amino-2-substituted-4-pyrimidinecarboxylic acids and their derivatives and their use as herbicides. It has now been discovered that certain esters of 4-amino-6-(substituted phenyl)picolinic acids and of 6-amino-2-(substituted phenyl)-4-pyrimidinecarboxylic acids can provide superior weed control especially in rice and wheat cropping systems and in pasture management programs.